2(3a+2b)(2b-3a)-(3a+2b)^2-(3a-2b)^2
问题描述:
2(3a+2b)(2b-3a)-(3a+2b)^2-(3a-2b)^2
答
2(3a+2b)(2b-3a)-(3a+2b)^2-(3a-2b)^2
=-[(3a+2b)^2-2(3a+2b)(2b-3a)+(3a-2b)^2 ]
=-[(3a+2b)^2+2(3a+2b)(3a-2b)+(3a-2b)^2 ]
=-[(3a+2b)+(3a-2b) ]^2
=-(3a+2b+3a-2b) ^2
=-(6a) ^2
=-36a^2